Question

For what value of 'm', the equation $(3m+1)x^2+2(m+1)x+m=0$ have equal root?

• A. $1,-1/2$
• B. $2$ or $4$
• C. $4$
• D. $3$

Answer 1

The correct option is A $1,-1/2$

For equal roots $D=b^2-4ac=0$

$\Rightarrow \left[2\right(m+1){]}^2-4m(3m+1)=0$

$\Rightarrow m^2+2m+1-3m^2-m=0$

$\Rightarrow -2m^2+m+1=0$

$\Rightarrow 2m^2-m-1=0\Rightarrow (m-1)(m+\frac{1}{2})=0$

$\Rightarrow m=1,\frac{-1}{2}$